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From: Ming Lei <ming.lei@redhat.com>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: "Martin K . Petersen" <martin.petersen@oracle.com>,
	"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
	Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	Bart Van Assche <Bart.VanAssche@wdc.com>,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	Stanislav Nijnikov <stanislav.nijnikov@wdc.com>,
	Evan Green <evgreen@chromium.org>,
	Vinayak Holikatti <vinholikatti@gmail.com>,
	Janek Kotas <jank@cadence.com>,
	Vivek Gautam <vivek.gautam@codeaurora.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Subhash Jadavani <subhashj@codeaurora.org>,
	Sayali Lokhande <sayalil@codeaurora.org>,
	Li Wei <liwei213@huawei.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Jaegeuk Kim <jaegeuk@kernel.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Alex Lemberg <Alex.Lemberg@sandisk.com>
Subject: Re: [PATCH RFC] scsi: ufs: Disable blk-mq for now
Date: Fri, 14 Sep 2018 09:52:38 +0800	[thread overview]
Message-ID: <20180914015237.GC11059@ming.t460p> (raw)
In-Reply-To: <e4d0c716-006a-72cb-0240-4ae5749b21b8@intel.com>

On Thu, Sep 13, 2018 at 03:15:39PM +0300, Adrian Hunter wrote:
> On 13/09/18 15:05, Ming Lei wrote:
> > On Thu, Sep 13, 2018 at 02:28:48PM +0300, Adrian Hunter wrote:
> >> blk-mq does not support runtime pm, so disable blk-mq support for now.
> > 
> > So could you describe a bit what the issue you are trying to fix?
> 
> UFS is a low-power solution, so we must be able to runtime suspend.
> 
> > 
> > This is host level runtime PM you are trying to address, and if blk-mq
> > runtime isn't enabled, I guess the host won't be runtime suspended at all
> > because some of its descendant are always active.
> > 
> > So seems we need to do nothing for preventing the host controller from
> > entering runtime suspend.
> 
> We don't want to prevent the host controller from runtime suspending, quite
> the opposite.

OK, got it.

However, in previous discussion, it is strongly objected to use
per-driver/device .use_blk_mq switch, so not sure if this way can
be accepted.

BTW, I just posted the runtime PM enablement patches[1] for blk-mq,
and I verified that it works fine and passed blktests & xfstest & my
other sanity tests, could you try it on UFS?

[1] https://marc.info/?l=linux-block&m=153684095523409&w=2

Thanks,
Ming

  reply	other threads:[~2018-09-14  1:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13 11:28 [PATCH RFC] scsi: ufs: Disable blk-mq for now Adrian Hunter
2018-09-13 12:05 ` Ming Lei
2018-09-13 12:15   ` Adrian Hunter
2018-09-14  1:52     ` Ming Lei [this message]
2018-09-14  6:17       ` Adrian Hunter
2018-09-14 13:03         ` Adrian Hunter
2018-09-20  6:58       ` Christoph Hellwig
2018-09-21  1:59 ` Martin K. Petersen

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